Advanced Materials Research Vols. 634-638

Abstract: A vapor deposed LiFePO4/C composite cathode material was acquired through filled carbon to FePO4 precursor by vapor deposition. The results showed that the carbon could contact to LiFePO4 nanopaticle directly and uniformly and formed a conducting network. It showed a good discharge capacity retention at large discharge rate. It was 57.3% at 10C. It also showed an excellent capacity steady characteristic when cycling at 1C.

Abstract: The geometrical structure of Y3Al5O12 (YAG) crystal was optimized by using first-principles calculation scheme, i.e. generalized gradient approximation (GGA) with the PW91 exchange correlation potential and “on the fly” pseudo-potential (OTFPP). The obtained lattice parameters are in good accordance with experimental results reported in the literature. This confirms the validity of the present GGA-OTFPP scheme. The total energy, populations, and contour maps of total charge density of YAG system were calculated with the same scheme. The derived formation energy (-2.396eV) indicate the good stability of the structure. The obtained Mulliken charge populations of atoms, overlap populations, as well as contour maps of total charge density congruously show that YAG crystal is a mixed bond material with stronger ion bond and weaker covalence bond.

Abstract: Structure, electronic property, aromaticity and vibrational frequency of medium-sized Au-doped germanium clusters were systematically explored using the density-functional theory (DFT) in conjunction with the LanL2DZ basis set. Our results show that the endohedrally Au-doped cagelike structures are energetically preferred. The p- and d-states in endohedral Au atom mainly contribute to the chemical bonding at around −6.5 and −10.6 eV for the AuGe10 and AuGe12 clusters. Moreover, the cage aromaticity appears to be an important determination of the electronic stability of the two clusters, reflected by negative nucleus-independent chemical shifts (NICS) values. The theoretical work will be useful and helpful for the understanding in the further application, i.e., cluster-assembled optoelectronic nanomaterials.

Abstract: Poly(m-trifluoromethylaniline) (PMTFMA) was synthesized on ITO/glass by using electrochemical method and the effect of different reaction conditions such as scan rate, the concentrations of monomer and sulfuric acid, and cycle times on the PMTFMA was studied. The resulting PMTFMA was characterized by FT-IR and UV-vis spectroscopy. The surface morphology of porous shape was recorded by scanning electronic microscope (SEM). It was found that the color of the polymer can turn from light yellow to yellow reversibly by increasing the applied voltage.

Abstract: The structural and electronic properties of Ti-doped SnO₂ with 6.25 at.% are investigated with the first principle calculations based on the density functional theory within the generalized gradient approximation. The calculation results indicate that the crystal structure of Sn_0.9375Ti_0.0625O₂ possesses a smaller volume; the bond length of Ti-O is shorter than that of Sn-O; the relative angle θ change value of Sn-O-Sn→Ti-O-Ti is about 1.07%. Ti-O bond possesses more covalent ingredient and stronger bond energy than Sn-O bond. After the replacement of one Ti atom, O atom bonded with Ti atom possessed fewer electrons, the ratio of charges possessed by Ti atom and O atom dose not agree with the stoichiometry of compound, create more holes at the top of VB of Sn_0.9375Ti_0.0625O₂, and lead to the increase of the conductivity.

Abstract: La0.9Sr0.1Ga0.8Mg0.2O3-d (LSGM) electrolyte materials were synthesized using solid state reactions. The LSGM material film was deposited by radiofrequency magnetic sputtering on La0.7Sr0.3Cr0.5Mn0.5O3-d (LSCM) substrates. The analysis results show the films did not form but formed some “mountains” when deposited for 4 h. While the depositing time extended to 12 h, a dense and uniform film with perovskite phase was obtained, and the element amounts of the film were closed to those of the LSGM materials.

Abstract: The First-principles based on plane-wave pseudo-potentials methods was applied to investigate the lattice parameter, electronic structure and optical property of Al2O3 (0001 ) by Ti Ion implantation . The calculation result show that the color center is form by transfer electron between 3d of Ti ion orbit energy level and Al ion 3p orbit energy level. and the absorption peak is located at the region of 2.1eV, which located in 400nm-450nm,where corresponding to the color and the color was caused by F color center

Abstract: Tm³⁺/Er³⁺/Yb³⁺ co-doped oxyfluoride tellurite and germanate glasses have been synthesized by conventional melting method. Intense up-conversion (UC) luminescence emissions were simultaneously observed under 980 nm excitation at room temperature in two glasses. The possible UC mechanisms are discussed and estimated. However, in the studied Tm³⁺/Er³⁺/Yb³⁺ co-doped oxyfluoride glasses, tellurite glass showed weaker UC emissions than germanate glass, which is inconsistent with the prediction from the difference of maximum phonon energy between oxyfluoride tellurite and germanate glasses. Absorption spectrum and Raman spectroscopy were employed to investigate the origin of the difference in UC luminescence in two glasses. Our results confirm that, besides the maximum phonon energy, the phonon density of host glasses is another important factor in determining the UC efficiency.

Abstract: All precipitate morphologies in Mg-8.8%Hg-8%Ga alloy for a range of aging temperatures are investigated in details using SEM, TEM and OM. The results show that Mg21Ga5Hg3 is the dominant precipitate in Mg-8.8%Hg-8%Ga alloy and precipitates in dispersed particles. This study elaborates on the morphological evolution of Mg21Ga5Hg3 precipitates as a function of aging time and temperature.

Abstract: An Agilent E4980A precision the LCR meter was used to estimate the effect of frequency, moisture content, position, location and variety on dielectric properties for biomass material of tobacco stems at microwave frequency of 2MHz. The dielectric properties of tobacco stems were significantly affected by frequency and moisture content. Both dielectric constant and dielectric loss factor rapidly declined first and then slowed with increasing frequency at lower moisture content. Increasing the moisture content, dielectric constant increased with the increasing frequency by orders of magnitude, while dielectric loss factor increased first and then decreased with dielectric relaxation emerging, where the dipolar relaxation frequency and the max of the dielectric loss factor also increased. Dielectric properties of the biomass material of tobacco stem were also affected by position, location and variety to some degree. The dielectric properties variation of K326 and Yun 87 was similar to each other which reflected their same genetic characteristics. At the frequency of 2MHz, dielectric constant and dielectric loss factor were mainly at 50-100 and 0.005-0.020, respectively.